'This is the end': Alaska Airlines passengers sue over door plug blowout

Four passengers are suing Alaska Airlines and Boeing for the "terror" they say they experienced after a door plug "blew off" during their flight, according to a complaint filed Tuesday.

The door plug for the fuselage of a Boeing 737 Max 9 fell off a few minutes after Alaska Airlines Flight 1282 took off from Portland International Airport on Jan. 5, depressurizing the cabin and exposing passengers to open air thousands of feet above the ground, according to the National Transportation Safety Board. No one was seriously injured and the plane made an emergency landing safely.

Two California residents and two Washington state residents who were on the flight are suing the two companies for alleged injuries including "intense fear, distress, anxiety, trauma [and] physical pain," according to the complaint.

"Plaintiffs feared the gaping hole in the fuselage, rapid depressurization, and general havoc was a prelude to the plane's destruction and their own likely death," the complaint stated.

"This is the end," one plaintiff thought, according to the complaint.

Some passengers also sent "what they thought would be their final text messages in this world," according to Seattle attorney Mark Lindquist, who filed the complaint on behalf of the four passengers.

One plaintiff texted, "Mom our plane depressed. We're in masks. I love you," according to the complaint.

The lawsuit alleges that Boeing delivered a plane with a faulty door plug and that Alaska management had deemed the aircraft unsafe to fly over the ocean but continued to fly it over land, according to the complaint.

In an interview with ABC News on Jan. 7, NTSB Chair Jennifer Homendy said Alaska pilots had reported a pressurization alert on that plane three times between Dec. 7 and Jan. 4, but it was determined to be benign. According to Homendy, Alaska ran maintenance tests and put the plane back in service, but issued a restriction for the plane to not fly over water to Hawaii. The plane had been in operation since Oct. 31, federal records show.

The lawsuit, which was filed in King County Superior Court in Washington state, is seeking unspecified damages for alleged negligence against Boeing and Alaska Airlines. It also alleges product liability against Boeing under the Washington Product Liability Act, alleging that the plane was "unreasonably dangerous and defective," according to the complaint.

The incident remains under investigation by the NTSB.

"Though it's too soon to know for sure what exactly went wrong," Lindquist said in a statement. "We do know Boeing is ultimately responsible for the safety of their planes and Alaska Airlines is ultimately responsible for the safety of their passengers."

Alaska Airlines grounded its Max 9 fleet shortly after the incident occurred. In response to the lawsuit, Alaska Airlines said it cannot comment on pending litigation.

Boeing had no comment on the lawsuit.

The Federal Aviation Administration grounded approximately 171 Boeing 737 Max 9 planes worldwide in the wake of the incident.

The FAA also is increasing its oversight over Boeing and began an audit of the company's production and manufacturing last week.

Spirit AeroSystems -- which produces the fuselage of the Boeing 737 Max 9 and was not named as a defendant in the lawsuit -- said it is "committed" to supporting the FAA's audit of Boeing's production line and suppliers.

"Spirit AeroSystems is committed to supporting the FAA's audit of production and manufacturing processes to ensure compliance with the FAA Quality Management System. As a trusted partner to our customers, Spirit's top priorities are quality, product integrity and compliance," Spirit AeroSystems said in a statement.

During a meeting with employees at the 737 production facility in Renton, Washington, last week, Boeing CEO Dave Calhoun said the company is "going to approach" the incident by starting with an acknowledgment of "our mistake."

"We're going to approach it with 100% and complete transparency every step of the way," Calhoun said during the meeting. "We are going to work with the NTSB who is investigating the accident itself to find out what the cause is."

The incident could have been potentially more "catastrophic" under different conditions, according to Homendy. The two seats next to the missing door plug were empty, and the incident occurred about 10 minutes after takeoff -- when passengers would have still had their seatbelts on -- at about 16,000 feet.

"At 30,000, at 35,000 feet, the pressure differential is much greater, which means it would have been a much greater, explosive event -- every violent -- and it could have had catastrophic consequences," Homendy told ABC News.

Alaska Airlines has offered full refunds to all passengers of Flight 1282, as well as a $1,500 cash payment "to cover any incidental expenses to ensure their immediate needs were taken care of," the company said.

"My clients want accountability for Boeing and Alaska Airlines," Lindquist said in a statement. "They also want assurances that this isn't going to happen again to anyone."

Other passengers on Alaska Airlines Flight 1282 have sued Boeing over the incident in a proposed class-action suit.

ABC News' Clara McMichael contributed to this report.